The present disclosure relates generally to a transducer holder and nozzle, and particularly to a noise suppressing holder for use with an ultrasonic transducer.
Ultrasonic transducers are used in measurement systems that employ an electrically actuated signal source, typically a piezoelectric crystal, mounted in a mounting assembly fixed to a housing or wedge, or fixed directly to a conduit, to propagate ultrasonic signals through a medium flowing in the conduit. In applications where the medium has a low density, such as a gaseous medium, or where the size of the conduit or the signal path length through the medium raises considerations of crosstalk, the amount of signal energy that can be received through the medium is relatively small. Furthermore, because the signal propagates through the gas with a velocity different from and generally slower than its propagation velocity through the solid structure of the conduit, it can be difficult to find a suitable timing window in which the received signal can be dependably distinguished from ringing or other energy propagated directly through the conduit walls.
To some extent the problem of signal strength can be addressed by appropriate impedance matching and the use of a large-area diaphragm to couple the crystal to the medium. However, suitable isolation remains a problem, particularly in view of the relatively large amount of energy contained in the solid-path noise band. Accordingly, there is a need in the art for an ultrasonic transducer holder that addresses problems associated with crosstalk and short circuit noise.